We plan to study changes in enzyme reactions by histochemical methods in the lens epithelium of rabbits after x-irradiation or mechanical injury. We want to compare changes previously determined in acid phosphatase with two enzymes considered to be lysosomes; B-glucuronidase and desoxyribonuclease. Specimens (flat lens mounts) will be prepared at intervals from 1 to 80 days after the challenge. Changes in enzyme concentration demonstrated by histochemical reaction will be determined by a densitometer. Other enzymes will also be studied to determine if changes occur similar to those seen in acid phosphatase. Previous studies have indicated malate and lactate dehydrogenases and dehydrogenase co-factor ubiquinone do not show similar changes. Enzymes to be studied include succinate, glutamate, lactate, malate, glycerophosphate, and glucose-6-phosphate dehydrogenases, gamma-amino-butyric decarboxylase, cytochrome oxidase, hexokinase, and glutathione reductase. Also, oxygen consumption after exposure to x-irradiation will be studied and compared to histochemical changes in the lens epithelium.